16 Psyche
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| Discovery A (http://cfa-www.harvard.edu/iau/lists/NumberedMPs.html) | |
|---|---|
| Discoverer | Annibale de Gasparis |
| Discovery date | March 17, 1852 |
| Alternate designations | B (http://cfa-www.harvard.edu/iau/MPDes.html) |
| Category | Main belt |
| Orbital elements C (http://asteroid.lowell.edu/) Epoch October 22, 2004 (JD 2453300.5) | |
| Eccentricity (e) | 0.140 |
| Semi-major axis (a) | 436.921 Gm (2.921 AU) |
| Perihelion (q) | 375.958 Gm (2.513 AU) |
| Aphelion (Q) | 497.884 Gm (3.328 AU) |
| Orbital period (P) | 1823.115 d (4.99 a) |
| Mean orbital speed | 17.34 km/s |
| Inclination (i) | 3.095° |
| Longitude of the ascending node (Ω) | 150.352° |
| Argument of perihelion (ω) | 228.047° |
| Mean anomaly (M) | 323.379° |
| Physical characteristics | |
| Dimensions | 253.2 km 1 (http://dorothy.as.arizona.edu/DSN/IRAS/IMPS/diamalb.tab) |
| Mass | 1.7×1019 kg |
| Density | 2.0 g/cm³ 2 (http://www.psi.edu/pds/archive/density.html) |
| Surface gravity | 0.0708 m/s² |
| Escape velocity | 0.1339 km/s |
| Rotation period | 0.1748 d (4.196 h) 3 (http://www.astrosurf.com/aude-old/map_files/AstVarMAP01-2003.htm) |
| Spectral class | M |
| Absolute magnitude | 5.90 |
| Albedo | 0.12 4 (http://dorothy.as.arizona.edu/DSN/IRAS/index_iras.html) |
| Mean surface temperature | ~167 K |
16 Psyche (sye'-kee) is the 13th-largest Main belt asteroid, measuring 250 kilometers in diameter.
It was discovered by Annibale de Gasparis on March 17, 1852 from Naples and named after the Greek nymph Psyche.
Spectral and other analyses indicate a fairly pure iron-nickel composition. Psyche and other class M asteroids originate from the metallic core of a large differentiated planetesimal similar to asteroid 4 Vesta.
Psyche is massive enough that its perturbations on other asteroids can be measured, which enables accurate mass and density values. Its density turns out to be extremely low, indicating extreme porousity or (less likely) a non-metallic composition. In other words, the asteroid is probably a gigantic rubble pile. (1) (http://homepage.mac.com/brother_guy/.cv/brother_guy/Public/Asteroid%20Densities.pdf-link.pdf)
Only one stellar occultation event by Psyche has so far been observed (from Mexico on March 22, 2002). Lightcurve variations indicate a non-spherical body.
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| (For a complete listing, see: List of asteroids. For pronunciation, see: Pronunciation of asteroid names.) |